Signaling by electromagnetic waves.



No. 793,652. PATENTED JULY 4, 1905.

R. A. FESSENDEN.

No. 793,652. PATENTED JULY 4, 19 05. R. A. FESSENDBN.

SIGNALING BY ELEGTROMA GNETIG WAVES.

APPLICATION FILED APR. 6, 190a.

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. ATTOR/VEK No. 793-u652. PATENTED JULY 41v 1905, R. A. FESSENDEN.

SIGNALING BY ELECTROMAGNETIC WAVES.

APPLICATION IILED APR. 6, 1905.

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V QM -wm PATENTED JULY 4, 1905.

R. A. FESSENDEN.

SIGNALING BY ELECTROMAGNETIC WAVES.

APPLICATION FILED APR. 6. 1905.

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lINVENTOR Atty llqill IIIIII WITNESSES: l

STATES Patented July 4., 1905.

PATENT OFFICE.

SIGNALING BY ELECTROMAGNETIC WAVES.

SPECIFICATION forming part of Letters Patent No. 793,652, dated July 4,1905.

Application filed April 6. 1905. Serial No. 254,129.

To all whom, it may concern.-

Be it known that I, REGINALD A. FEssEN- DEN, a citizen of the UnitedStates, residing at ashington, in the District of Columbia, haveinvented or discovered certain new and useful Improvements in Signalingby Electromagnetic Waves, of which improvements the following is aspecification.

The invention described herein relates to certainiimprovements insignaling by electromagnetic waves,and has for itsobject the provisionof means for the controlled production of radiations from the aerial.

It is a further object of the invention to provide for the reception ofsignals from one station while sending signals to another station.

The invention is hereinafter more fully described and claimed.

In the accompanying drawings, forming a part of this specification,Figure 1 is a diagrammatic view of sending and receiving circuits at astation in connection with a selector.

Fig. 2 is a similar view illustrating a modification. Fig. 3 isadiagrammatic view illustrating the manner of simultaneously receivingand sending signals. Fig. 4 is a side elevation of a desirable form ofselector and commutator. Fig. 5 is an end elevation of the selector.Fig. 6 is an end elevation of the com-.

mutator, and Fig. 7 is a view illustrating the operation of thecommutator.

In the practice of my invention as illustrated in Figs. 1 and 2 theaerial, which is preferably of the construction shown and described inapplication for Letters Patent, Serial No. 252,942, filed March 30,1905, is connccted by a switch 2 with either the receiving mechanism(indicated at 3) or with the sending mechanism. For sending the primaryof the transformer 4 is connected to a suitable source of alternatingcurrents, such as the dynamo 5, which, with its exciter 6, is driven bya suitable motor 7. A transformer of high voltage, preferably from fiftythousand to one hundred thousand volts, is employed unless the methoddescribed in Letters Patent No. 706,737 is used, when a lower voltagemay be used. As shown, the current through the primary of thetransformer 4 is regulated by a suitable means, as a relay, (indicatedat 8,) and controlled by the key 9 or other suitable means. The currentthrough the primary of the transformer is adjusted by suitable means,(indicated at 10.) One of the terminals of the secondary of thetransformer is connected, through the adjustable inductance orautotransformer 11 and condenser 12, to a contact 13 and the otherterminal of thesecondary to a contact-plate 14 through an adjustableresistance 15, whereby the amount of surging or oscillating may beregulated while the condenser 12 is being changed. Contact-plates 16 and17 are arranged intermediate of the contacts 13 and 14 and whenelectrically connected, as hereinafter described, form portions of aclosed circuit including the condenser 12 and inductance 11 in operativerelation to the aerial 1. One or more pairs of arms 18, 19, 20, and 21are so arranged that when rotated they will contact with or be broughtinto operative relation to the pairs of plates 13, 14, 16, and 17. Thearms of each pair and the plates of each pair are so arranged relativelyto each other that when one arm, as 18, is in contact with one plate, as13, the other arm 19 of the pair will be in contact with plate 14 andwhen the arm 18 moves to the plate 16 the arm 19 will be in contact withplate 17 The arms should be so rotated that the charging and dischargingof the condenser will occur at a time of maximum potential of thealternating current and by the employment of a sulficient number of armsmay occur at every period of maximum potential.

It is preferred, however, that this charging and discharging shouldoccur at every fourth period of maximum potential, so that if the dynamois a sixty-cycle machine the charging and discharging will occur thirtytimes a second. While the arms may be driven in any suitable manner, itis preferred that they should be rotated by the shaft 'of the generator5.

A convenient construction of selector is shown in Figs. 4 and 5, wherethe contactplates 13, 14, 16, and 17 are formed by pins adjustablymounted on arms 22 and 23,loosely mounted on the shaft 24,connected tothe shaft of the generator 5. The pins are mounted in blocks ofinsulating material secured to the arms 22 and 23, which can be adjustedas regards their angular separation by any suitable meanssuch, forexample, as that shown. The arms 18, 19, 20, and 21 are formed by radialpins secured in a disk 25, mounted in the shaft 24. ,Diametricallyopposite pins are electrically connected, butinsulated from adjacentpins, as shown.

In the construction shown in Fig. 1 the movable members of the selectorare brought into operative relation to the other members atregularly-recurrent intervals, and the radiation from the aerial isdependent upon the flow of current through the transformer 4, such flowbeing regulated by the key 9. In other words, the charging of thecondenser is regulated, and its discharge follows at regular intervalsthereafter. In lieu of regulating the charging of the condenser itscharging may be continuous at regular intervals and its dischargeregulated by a key, as shown in Fig. 2. As shown therein, provision ismade for so shifting one contact-plate, as 17, in thedischarging-circuit that although the arms 18, 19, 20, and 21 rotatecontinuously and the condenser is connected at regular recurrentintervals to the source of alternating current the discharge iscontrolled by the operator. This control can be conveniently had by theemployment of magnetic means for shifting the plate 17. In theconstruction shown the plate 17 is secured to the core of the solenoid26,the coil thereof being in a circuit controlled by the key 9. Whenthis method is employed for multiplex sending, a number of movablecontact-plates, each operated by its own key, are employed. It will beobserved that when employing the selector for sending there will becertain short intervals between the charging and discharging of thecondenser. By the employment of suitable means these intervals may beutilized for receiving.

In Fig. 3 a system for simultaneous sending and receiving isdiagrammatically shown. The circuit containing the inductance 27 andcondenser 28 is tuned, by preference, to the sending -conductor. Whenusing a transformer, as indicated at 29, to charge the condenser, it ispreferably adjusted to have a secondary voltage of twenty-five thousandvolts. When desired, an adjustable resistance 30 may be employed fordampening unnecessary oscillations.

As described in connection with the apparatus shown in Figs. 1 and 2, aselector consisting of stationary and movable members is employed,whereby the condenser 28 is alter natel y placed in charging relation tothe transformer 29 and in discharging relation to the sending-conductor.This selector is indicated in Fig. 3 by a movable conductor 31 andcontact-plates 32, 33, 34, and 35; but it will be understood by thoseskilled in the art that the construction of selector shown in Figs. 1,4,

and 5 may be employed and that radiation from the sending conductor maybe controlled, as shown in Fig. 1, by controlling the flow of current inthe transformer, or by controlling the discharge of the condenser, as

shown in Fig. 2. The aerial 1 is connected to The aerial is connected toa brush 36, while the brush 37 is connected to ground. The brushes 38,39, and 40 are connected to portions of the receiving apparatus. Theprimaries 44 and 45 of an interference-preventer, as described inapplication, Serial No. 240,269, filed January 9, 1905, and variablecondensers 46 and 47 are connected in parallel to brushes 38 and 40. Thevariable condensers 46 and 47 are adjusted to have equal capacity, sothat when the variable condenser 48 is not in circuit the circuits 44 46and 45 47 will respond equally well to any frequency, but when condenser48 is in circuit one of the circuits, as 44 46, will respond to adifferent frequency from that to which the circuit 45 47 will respond.The secondaries 49 50 are connected in series to a suitable receiver 51.The rotation of the commutator-spool should bear a constant relation tothat of the movable portion of the selector, and as the movement of themovable portion of the selector should have a-constant relation to therotation of the movable element of the generator the commutator-spooland the movable element of the selector are operated by the shaft of thegenerator.

The brushes 36, 37, 38, 39, and 40 and the commutator-segments are sofixed relatively to the angular position of the movable conductor 31that when the conductor is in the position shown in full lines, at whichtime the condenser 28 will be discharged, the aerial will be connectedto ground. While the movable conductor is moving from charging todischarging position and. from the latter to charging position thebrushes and segments of the commutator have the relative positionsindicated by dotted lines in Fig. 7, so that aerial is connected throughthe condenser 28 to brush 36, thence through segment 52 to brush 38,thence through the receiver-circuit containing the interferencepreventer to brushes 39 40, and thence through commutatorsegment 53 andbrush 37 to ground. While these connections are established thereceiving-circuits and mechanism are in operative relation to the aerialand messages can be received.

By the continued movement of the conductor 31 and the commutator theformer will be.

brought to condenser charging or discharging position and the segmentsand brushes of the commutator to positions indicated in full lines inFig. 7. In this position the aerial is connected to ground throughbrushes 36 and 37 and segment 54:. At the same time the recei vercircuitis short-circuited by the connection of the brushes 38 and 39 by thesegment 55, and the condenser 48 is insulated, as the brushes 40 Willrest on an insulated portion of the commutator and the circuits 4:4: 456and 47 are balanced, and no eifect is produced on the receiver.

It Will be understood that in connection with the system shown in Fig. 3suitable means, such as shown in Figs. 1 and 2, are employed forcontrolling the charging or discharging of the condenser, and therebythe radiations from the aerial.

I claim herein as my invention- 1. In a system of signaling byelectromagnetic Waves the combination of an aerial, acharging-circuit,"a discharging-circuit and means for connecting theaerial alternately to the charging and discharging circuits.

2. In a system of signaling by electromagnetic waves the combination ofan aerial, a condenser, a source of alternating current and means forconnecting the condenser to the aerial and the source of alternatingcurrent at periods of maximum potential.

3. In a system of signaling by electromagnetic waves the combination ofan aerial, a condenser, a source of alternating current and means forconnecting the condenser alternately to the aerial and the source ofalternating current at periods of maximum potential.

4. In a system of signaling by electromagnetic waves the combination ofan aerial, a condenser, a source of alternating current, means foralternately placing the condenser in operative relation to the aerialand the source of current and means for varying the potential in thecondenser (i. a. charging or discharging the condenser).

5. In a system of signaling by electromagnetic waves the combination ofan aerial, a

condenser, a source of alternating current and a rotary conductor forplacing the condenser in operative relation alternately to the aerialand the source of current.

6. In a system of signaling by electromagnetic waves the combination ofan aerial, a condenser, a sourceof alternating current and a movableconductor for alternately placing the condenser in operative relation tothe aerial and the source of current at periods of maximum potential.

7. In a system of signaling by electromagnetic waves the combination ofan aerial, a condenser, an alternating-current generator, and a movableconductor operated by the generator for alternately placing thecondenser in operative relation to the aerial and the generator.

8. In a system of signaling by electromagnetic Waves the combination ofan aerial, receiving mechanism, means for the continuous generation ofelectromagnetic Waves, continuously-operating means for placing theaerial in operative relation alternately to the receiving mechanism andthe generating means.

9. In a system of signaling by electromagnetic waves the combination ofan aerial, a condenser, a source of alternating current, means foralternately placing the condenser in operative relation to theaerial andthe current source, a receiving-circuit and means for connecting theaerial to the receiving-circuit at times intermediate of'the connectionof the condenser With the aerial.

10. In a system of signaling by electromagnetic Waves the combination ofan aerial, a condenser, means for alternately charging the condenser anddischarging it through the aerial, a receiving-circuit and means forconnecting the receiving-circuit to the condenser, intermediate of thecharging and discharging periods.

11. In a system of signaling by electromagnetic waves the combination ofan aerial, a sending-circuit, a receiving-circuit andcontinuously-operating means for placing said circuits alternately inoperative relation to the aerial.

12. In a system of signaling by electromagator for placing the condenserin operative relation alternately With the aerial and the IIO generator,a receiving-circuit and a commutator operative by the generator forconnect ing the receiving-circuit to the condenser 1ntermediate of thecharging and discharging operating commutator for connecting the aerialalternately to the receiving and sending circuits.

In testimony whereof I have hereunto set my hand.

REGINALD A. FESSENDENF Witnesses:

THOMAS 1. BROWN, LEONA FEATHERS.

